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Radiation — Radiation, as in physics, is energy in the form of waves or moving subatomic particles emitted by an atom or other body as it changes from a higher energy state to a lower energy state. Radiation can be classified as ionizing or non ionizing… … Wikipedia

radiation — [rā΄dē ā′shən] n. [L radiatio] 1. the act or process of radiating; specif., the process in which energy in the form of rays of light, heat, etc. is sent out through space from atoms and molecules as they undergo internal change 2. the rays sent… … English World dictionary